1. Field of the Invention
The invention relates to automatic starters for an internal combustion engine and, more particularly, to a circuit for automatically starting the engine at a predetermined time. More specifically the invention concerns an automatic starter for an automotive vehicle.
2. Prior Art
A variety of automatic systems for starting the engines at a predetermined time or from remote locations are well known. These systems provide the convenience of warming up the engine prior to the operator entering the vehicle so that it is ready to be driven immediately. This is particularly advantageous in the northern states during the winter where it takes a much longer time for the engine to warm up. Often the driver must sit in a cold automobile for a period of time even before he can move the vehicle, and then he must drive for several minutes before the engine warms up sufficiently to permit the heater to warm the interior. If the automobile can be automatically started a few minutes before the operator is ready, this inconvenience can be eliminated. A similar advantage is also available during the summer when the interior of the automobile becomes unbearably hot after sitting in the sun for any length of time. Under this condition, the capability of starting of the engine and turning on the air conditioner a short time before the operator enters the vehicle permits the interior to be cooled to a more tolerable temperature.
Automatic starting mechanisms range from the relatively simple system taught by Davis in U.S. Pat. No. 2,949,104 (August, 1960) which embodies a timer activating a relay through a vacuum switch. The vacuum switch terminates power to the starter relay when the engine starts and a vacuum is generated in the engines air intake manifold. This system provides no means for terminating power to the starter relay in event the engine fails to start which could eventually drain the battery. Ives in U.S. Pat. No. 3,151,249 (September, 1964) provides a mechanically actuated switch which terminates power to the starter relay after about 20 seconds to prevent draining the battery but is only capable of energizing the starter during the first 20 second interval. If the engine stops after this time, the circuit is incapable of restarting the engine. With this circuit it is possible within the 20 second interval to have a restart attempt before the engine stops from a prior start which could possibly damage the starter mechanism. Ives also teaches a throttle solenoid which advances the throttle to set the automatic choke facilitating starting of a cold engine. McWhirter in U.S. Pat. No. 3,259,753 (July, 1966) provides a stepper motor providing for a predetermined number of start attempts determined by the operator and a thermal switch to limit each start attempt to 10 seconds. After the predetermined number of start attempts, the stepper motor is deenergized terminating all subsequent start attempts. McWhirter teaches deenergizing the automatic starting system after the engine has started in response to the output from the generator. This method permits a restart attempt after a false start, (i.e. engine starts then dies as is common when starting a cold engine) and attempts a restart before the engine comes to a rest which could possibly damage the starting mechanism. In this system, the foot pedal is held in a fixed depressed position by a mechanical clamp and the automatic choke must be manually set by the operator. Fenner in U.S. Pat. No. 3,220,397 (November, 1965) teaches the use of a centrifugal switch in the starter relay circuit to prevent a restart attempt with the engine still turning after a false start. The Kennedy patent likewise teaches deactuating the automatic starting system in response to an output from the generator. This system has the disadvantage that the automatic choke and/or fast idle solenoid are not actuated until after the engine has started, which is the reverse of the normal operating procedure. Further, the thermal switch remains in the starter relay circuit even when the operator is attempting a manual start.
The disclosed automatic starting system overcomes the disadvantages of the prior art systems discussed above and closely follows the procedure followed by a human operator. It also provides an automatic shut down in event of a starter or engine failure and provides protection against a mechanical failure in the drive train of the vehicle.